This invention relates to what is commonly called a dock shelter whose purposes is to effect a seal against rain, snow and air currents between the body of a truck van and a building when a truck is being loaded or unloaded.
A variety of structures have been proposed for effecting a seal between a truck van and a building opening during loading and unloading operations. One generally known type of dock shelter or seal to which the improvements hereinafter discussed relate, comprises a substantially rigid frame that surrounds a door opening and has inwardly extending front side curtains and a top side curtain which defines an opening that is smaller than the expected dimensions of the van. U.S. Pat. No. 3,403,489 is an example. Traditionally, the curtains have been made of a water-repellant material such as canvas duck or rubber-impregnated nylon fabric. These materials are guite flexible so they are inclined to flap in the wind and lack the ability to maintain their shape which is a detraction from their functional and esthetic quality. Moreover, known types of prior art curtains are difficult to maintain in sealing relationship at their interfaces when the corners and edges defining the rear end of the van are pressed into them for the purpose of deflecting them and effecting a seal. They are also subject to being torn or abraded by the edges of the van repeatedly rubbing them. Hence, many different schemes have been proposed for reinforcing the curtains in their main areas of wear. Use of plastic sheets laid out in a shingle arrangement in the high wear areas represents one attempt to create a low friction reinforced area. Spring metal stays have been imbedded in the side curtains to obtain more compressive action by the curtain against the van and to overcome the inherent floppiness of ordinary fabric materials. A number of methods have been devised for producing a seal near the bottom edges of the side curtains such as letting the rear edge of the van run into stationary foam blocks. Although the above-mentioned problems have been addressed as indicated, their attempted solutions have not been considered satisfactory insofar as functionality, durability and esthetic qualities are concerned. The prior art also includes door seals having thick pads about the doorway and against which the truck backs. See U.S. Pat. Nos. 3,375,625 and 3,500,599, for example. In these devices the pads are compressed or deformed in use and are subject to heavy wear and abuse.